Processes of this type are to be distinguished from those wherein the wire is advanced with unretarded feeding speed also during the operation following the straightening step, especially a cutting procedure that follows straightening, and therefore the operating means performing the operation subsequently to the straightening step, e.g. a cutter for cutting the wire to length, must be moved along with the high feeding speed together with the wire. These processes, known, for example, from U.S. A-1,703,885, although exhibiting the advantage that the problem of heating up and damage (burning through, embrittlement, inhomogeneous strength of material) to the stationary wire in the rotating straightening rotor is obviated, but they have the drawback that the operating means moving along at the high wire feeding speed, e.g. the cutter designed as so-called "flying shears", is complicated in its structure and expensive. Japanese Patent No. A-58 122 139 also discloses a process of that other type wherein the wire continues to travel at an invariably high feeding speed, rather than intermittently, also during the subsequent operation. The wire straightening device known therefrom comprises several groups of conveying rollers for feeding the wire, adjustable shaping rollers, a straightening rotor with a cylindrical housing wherein three straightening blocks are arranged, and a wire scanning device checking the linearity of the straightened wire. An adjusting device is located in the housing of the straightening rotor, for the radial adjustment of the straightening blocks; this device can be connected, with the straightening rotor standing in a specific rotational position, by way of a clutch with a motor which latter can be displaced by a shifting device. The wire feeding speed and the angular velocity of the straightening rotor are calculated and set by a control device based on the wire diameter and the wire material. The straightening rotor can be connected selectively (apparently by way of a freewheel clutch) with an electric motor generating the angular velocity for the straightening step and with a stepping motor for rotating the rotor into the rotational position for setting the straightening blocks; the stepping motor is activated by the control device after the straightening rotor has ceased turning with the electric motor being stopped. Straightening here is interrupted only if a new wire having different properties is to be used, requiring a different setting of the straightening blocks.
The process of this type is also to be distinguished from those processes of another type wherein the wire is stopped during the procedure, especially during the cutting step, and the straightening rotor, with the wire being stationary, is moved in the axial direction (longitudinal direction of the wire) in order to prevent excessive squeezing work at one point and thus embrittlement or burning through of the wire. A process and apparatus of that other type has been known from U.S. A-2,172,134. In this reference, the straightening rotor is supported on a carriage movable to and fro on a pair of rods and is driven by way of a clutch. The carriage is respectively moved forwards during wire feed with the rotating straightening rotor and backwards with the rotating straightening rotor with the wire being stationary for cutting, clamped fixedly by means of grippers. At the end of the backward movement, the carriage abuts against a stop whereby the clutch is disengaged and the straightening rotor is allowed to run out. After cutting the wire to length, the grippers are opened and the carriage again moved forwards, the clutch being engaged and the wire piece, previously straightened during the backward travel of the carriage, moving through the grippers.
The complicated and trouble-prone, very rapid movement of the operating means, e.g. the so-called flying shears, and the movement of the straightening rotor in the wire direction (in the direction of the axis of the straightening rotor) is eliminated in the process of this type known from Swiss A-475,806. In this arrangement, the wire is cut off while standing still, and the straightening blocks of the rotating straightening rotor are moved during the period of standstill of the wire by hydraulic or pneumatic means radially in such a way that the squeezing work is reduced and thus embrittlement and burning through of the wire are prevented. Also the radial adjustment of the straightening blocks of the rotating straightening rotor is, however, complicated and susceptible to disturbances.